Intravenous (“IV”) therapy is typically provided to a patient using a disposable set. Previously, administrators had to confirm a fluid (e.g., drug) type, fluid concentration, or agent within a fluid to be administered by reading information on a drug container such as, for example, an infusion bag. However, administrators can misread the information on the container or forget to check the information on the container. Additionally, the fluid, agent and/or fluid/agent concentration within the container may not accurately reflect the actual fluid type or concentration. To reduce these errors and improve patient safety, sensors have been integrated within a portion of the disposable drug delivery set to provide a final verification before the fluid is infused into a patient.
Some of these known fluid detection sensors use optical sensing to determine a drug type and/or concentration. These optical sensors include Raman spectroscopy sensors and surface enhanced Raman spectroscopy (“SERS”) sensors. The sensors use light provided from an outside source, such as a laser, to detect properties in the fluid under measurement.
Raman spectroscopy sensors measure vibrational, rotational, and other low-frequency modes of a fluid. The sensors use for example, inelastic scattering or Raman scattering of monochromatic light from a laser in the visible, near infrared, and/or near ultraviolet range. The laser light interacts with molecular vibrations, phonons, and/or other excitations in the fluid, resulting in the energy of the laser photons being shifted up or down. The shift in energy provides information about the vibrational modes in the fluid. In practice, a sample fluid is illuminated with a laser beam. Light from the illuminated spot is collected with a lens and sent through a monochromator. Wavelengths close to the laser line resulting from elastic Rayleigh scattering are filtered out while the rest of the collected light is dispersed onto a Raman spectroscopy sensor for analysis.
SERS sensors operate under the same principles as Raman spectroscopy sensors. However, SERS sensors use a surface-sensitive detection technique that enhances Raman scattering by molecules absorbed on rough metal surfaces or nanostructures such as, for example, plasmonic-magnetic silica nanotubes. Similar to Raman spectroscopy sensors, SERS sensors use laser light to detect shifts in energy of the absorbed molecules. The use of SERS sensors requires that the sensor be in contact with the fluid under measurement. Known systems position SERS sensors within the tubing of a disposable set. However, placing the SERS sensor within the tubing reduces fluid flow, thereby frustrating infusion therapy.
Moreover, the use of SERS sensors and Raman spectroscopy sensors requires that the laser light travel through the tubing. The plastic composition of the tubing oftentimes interferes with the laser light, reducing sensing accuracy of the Raman spectroscopy sensors and/or the SERS sensors. A need accordingly exists for a disposable set that uses Raman spectroscopy sensors and/or SERS sensors having improved fluid flow, and which is able to provide relatively interference-free laser light.